The present invention relates to a contactless ignition system for internal combustion engines, which includes an ignition coil having two primary windings whose primary currents are alternately switched on and off by means of two power transistors.
In a known ignition system of the above type, a reverse current blocking diode is connected between each of the primary windings of an ignition coil and each of two power transistors each having a diode connected in inverse parallel therewith, whereby when one of the power transistors is turned off, the current is prevented from flowing back to the primary winding connected in series with the other power transistor. However, in addition to these diodes, a Zener diode must be connected between the collector and emitter or the collector and base of each of the power transistors to protect the transistor against excessive voltages.
Thus, the known ignition system of the above type has the disadvantage of requiring a large number of component parts and being high in cost due to the connection of a reverse current blocking diode and an overvoltage protection Zener diode to each of two power transistors.